Pollinator Germplasm as a Genetic Resource for Conservation

Science Center Objects

Honey bee colony failure is primarily due to the infestation of mites and agricultural pesticides, including neonicotinoids. USGS researches the impacts these have on honey bee reproductive capabilities.

 

Honey bee (Apis mellifera)
Honey bee (Apis mellifera)

The Science Issue and Relevance: Combating honey bee colony failure is a goal of beekeepers because the annual loss occurrence is becoming economically unsustainable. The overwinter 2014/2015 reported loss rate was ~23.1%; the goal put forth in the Pollinator Research Action Plan is to reduce this value to no more than 15% by 2025. Primary causes of hive failures include Varroa mites and systemic pesticides used on agricultural crops including neonicotinoids, the fastest growing class of insecticides globally which are banned in Europe. The mode of action of neonicotinoids is to bind tightly to the nicotinic acetylcholine receptor, blocking ion transport and neurotransmission. A research gap exists on the male reproductive effects caused by both of these stressors, as only anecdotal or sparse evidence is available. Fertility parameters are affected by both mite and pesticide stressors. Thus understanding the mechanisms involving germplasm quality informs the bee industry, and conservation efforts with honey bee genetic strains and with native pollinators. Honey bees are the “laboratory model” for native pollinators.

Methodology for Addressing the Issue: Honey bees (Apis mellifera) that have been exposed to either mites or neonicotinoid pesticides will be examined. Sperm cell viability, count, and acrosomal status will be measured in mature and immature drones. Mite infestation changes sperm glycoprotein expression that is important in egg-sperm binding.

Fluorescence microscopy of 9- (A) and 10-day old (B) mite-uninfested drone spermatozoa
Fluorescence microscopy of 9- (A) and 10-day old (B) mite-uninfested drone spermatozoa

Future Steps: Optimize methods for honey bee germplasm assessment, and storage. Assess honey bee and possibly bumble bee (Bombus sp.) germplasm from a reference and exposed field.